Description of the Prior Art
The basic combustion process underlying the invention involves the use of combustion wave energy to drive an air chamber in the piston of an I.C. piston engine in resonance to cause previously stored air in the air chamber to be literally dynamically pumped into the combustion chamber in a totally passive manner while the combustion/expansion part of the engine operating cycle is occurring, such pumping effect occurring even independently of the total average pressure differential between the air and combustion chambers. This process generally has been previously described in the published literature relating to the Naval Academy Heat Balanced Engine (NAHBE). See for example: United States Naval Academy Progress Report No. EW 8-76 entitled: "The Naval Academy Heat Balanced Engine (NAHBE)" by Blaser, Pouring, Keating and Rankin (June, 1976); United States Naval Academy Trident Scholar Report No. TSPR No. 112, (1981) entitled "Optimizing the NAHBE Piston Cap Design Utilizing Schlieren Photography Methods and Applications of the Helmholtz Theory" by William H. Johnson (June 2, 1981); United States Naval Academy Program Report No. EW-13-80 entitled: "Time Dependent Analytical and Optical Studies of Heat Balanced Internal Combustion Engine Flow Field" by Pouring and Rankin (November, 1980); United States Naval Academy Progress Report No. EW-10-78 entitled: "Preliminary Investigation of the Non-Steady Combustion and Flow Process of the Naval Academy Heat Balanced Engine (NAHBE)," (June, 1978), and United States Naval Academy Progress Report No. EW-12-79 entitled "Parametric Variations of a Heat Balanced Engine" by Failla, Pouring, Rankin and Keating. (September, 1979).
However, while the use of combustion wave energy to cause controlled pumping of air into a combustion zone of an IC engine has been demonstrated by the NAHBE Project, the pistons, combustion chambers and charge control systems of the prior NAHBE engines described in the literature essentially were experimentally derived through a series of design iterations until the model performed according to theoretical expectations, or at least approached such expectations. Many variables were experimented with in the environment of a single cylinder engine configuration, usually a laboratory experimental engine such as a Combustion Fuel Research (CFR) engine, and in some instances a multicylinder commercial production engine. A procedure was not evident, however, as to how one could determine the optimum dimensions constituting the geometric variables associated with the engine piston and cylinder, as well as suitable air to fuel ratios, without trial and error techniques that were laborious, time consuming, expensive and inexact. More frustrating was the discovery that even if one finally determined the optimum geometry and best charge composition for a single engine or engine family, it was not evident how one could extrapolate the geometric proportions or other variables to the next engine or engine family to produce the same result achieved in the first engine. The present invention contemplates an improvement to such an engine comprising a piston and combustion chamber geometry, and a charge management and control system for use with such piston and combustion chamber, that is operable with a variety of engines or engine families with a minimum of trial and error experimentation or iterations.
Since the concept of using wave interaction to improve combustion in NAHBE engines was largely experimental, previous engine designs were not concerned with managing the fuel and air charge much beyond assuring that stratification was achieved in the combustion chamber before compression began (very lean near the piston which contained the air chamber and rich near the opposite end of the combustion chamber) or beyond attempting to run the engine as economically as possible (e.g. as lean as possible) while achieving full power output. While theoretical studies indicated that the efficiency and power of a NAHBE engine should be better than an Otto or diesel, optimization to achieve such improvement in actual commercial engines was not readily at hand since a practical procedure for managing the charge automatically was not apparent. Charge management in the experimental NAHBE engines was achieved usually by manipulating valves to satisfy steady state operating conditions of the engine.